1. Field of the Invention
The present invention relates to disk drives for computer systems. More particularly, the present invention relates to a disk drive comprising a notched disk clamp for improved disk balance.
2. Description of the Prior Art
In disk drives, such as in xe2x80x9csingle-diskxe2x80x9d disk drives, a disk clamp clamps a disk to the hub of a spindle motor to form a xe2x80x9cdisk packxe2x80x9d. A head is actuated radially over the disk while the spindle motor rotates the disk at a predetermined angular velocity. It is important to manufacture the disk pack so that it is properly balanced to minimize disk wobble. One technique for achieving proper balance is to center the disk with respect to the hub; however, this increases the manufacturing cost by requiring extremely tight tolerances and/or sophisticated positioning mechanics while clamping the disk to the hub. Other techniques include decreasing the tolerance on the concentricity of the disk with respect to the hub and compensating for the imbalance using a micro-actuator in a feed-forward, servo control system. However, the micro-actuator and feed-forward servo control system increase the cost and complexity of the disk drive.
There is, therefore, a need to cost-effectively compensate for the imbalance of a disk pack in a disk drive caused by the non-concentric alignment of the disk with respect to the hub of the spindle motor.
The present invention may be regarded as a disk drive comprising a disk, a spindle motor for rotating the disk, and a head actuated radially over the disk. A disk clamp clamps the disk to a hub of the spindle motor, wherein the disk clamp comprises a notch at a predetermined location along an outer diameter of the disk clamp. The disk is aligned non-concentric with the hub such that a center of the disk is aligned offset from a center of the hub toward the notch. The notch substantially counteracts an imbalance due to the non-concentric alignment of the disk with respect to the hub. The notch may be formed from any suitable shape, including an arc shape or a square shape.
In one embodiment, an interior diameter of the disk presses against an outer diameter of the hub at a location substantially opposite the location of the notch.
The present invention may also be regarded as a method of manufacturing a disk drive. A disk is placed onto a hub of a spindle motor, and a disk clamp is placed over the disk. The disk clamp comprises a notch at a predetermined location along an outer diameter of the disk clamp. The disk is biased in a planar direction toward the notch while securing the disk clamp to the hub. The disk is aligned non-concentric with the hub such that a center of the disk is aligned offset from a center of the hub toward the notch. The notch substantially counteracts an imbalance due to the non-concentric alignment of the disk with respect to the hub.